Bacteria -research Material Essay, Research Paper

BACTERIA ( Gr. bakterion, & # 8220 ; small staff & # 8221 ; ) , group of microscopic, unicellular beings that lack a distinguishable karyon and that normally reproduce by cell division. are bantam, runing from 1 to 10 microns ( 1 micron peers 1/25,000 in ) , and are highly variable in the ways they obtain energy and nutriment. They can be found in about all environments-from air, dirt, H2O, and ice to hot springs ; even the hydrothermal blowholes on the deep ocean floor are the place of sulfur-metabolizing bacteriums ( see Marine Life ) . Certain types are found in about all nutrient merchandises, and bacteriums besides occur in assorted signifiers of mutualism ( q.v. ) with most workss and animate beings and other sorts of life. . the presently used five-kingdom strategy of categorization ( q.v. ) , bacteriums constitute the land Monera ( q.v. ) , besides known as Procaryotae-organisms in whose cells the karyon is non enclosed by a membrane ( see Cell ) . About 1600 species are known. Generally, bacteriums are classified into species on the footing of features such as shape-cocci ( domains ) , bacilli ( rods ) , spirochetes ( spirals ) ; cell-wall construction ; differential staining ( see Gram & # 8217 ; s Stain ) ; ability to turn in the presence or absence of air ( aerobes and anaerobes, severally ) ; metabolic or fermentative capablenesss ; ability to organize hibernating spores under inauspicious conditions ( see Spore ) ; serologic designation of surface constituents ; and nucleic-acid relatedness. most widely used mention for systematic categorization of bacteriums divides them into four major groups based on cell-wall features. The division Gracilicutes encompasses bacteriums with thin, gram-negative-type cell walls ; the Firmicutes have thick, Gram-positive cell walls ; the Tenericutes deficiency cell walls ; and the Mendosi-cutes have unusual cell walls made of stuff other than typical bacterial peptidoglycan. Among the Mendosicutes are the archaebacterium, a group of unusual beings that includes methanogens, rigorous anaerobes that produce methane from C dioxide and H ; halobacteriums, which grow at high salt concentrations ; and thermoacidophiles, which are sulfur-dependent utmost thermophiles. It has been argued that the archaebacterium should be classified into a separate land because recent biochemical surveies have shown that they are as different from other bacteriums as they are from eukaryotes ( the nucleii of which are membrane-bound ) . The four major bacterial divisions are farther subdivided into approximately 30 numbered subdivisions, some of which are divided into orders, households, and genera. Section 1, for illustration, is made up of spirochetes-long, corkscrew-shaped bacteriums with Gram-negative cell walls and internal ( between the cell wall and cell membrane ) filiform scourge that provide the beings with motility ( ability to travel ) . Treponema globus pallidus, doing pox, is a spirochete, a member of the order Spirochaetales, and the household Spirochaetaceae. all bacteriums can travel, but the motile 1s are by and large propelled by screwlike appendages-flagella-that may project from all over the cell or from one or both terminals, singly or in tussocks. Depending on the way in which the scourge rotate, the bacterium either travel frontward or topple in topographic point. The continuance of tallies versus toppling is linked to receptors in the bacterial membrane ; fluctuations enable the bacterium to travel toward attractants such as nutrient beginnings and off from unfavourable environmental conditions. In some aquatic bacteriums that contain iron-rich atoms, motive power has been found to be oriented to the Earth & # 8217 ; s magnetic field. . familial stuff of the bacterial cell is in the signifier of a round dual strand of DNA ( see Nucleic Acids ) . Many bacteriums besides carry smaller round DNAs called plasmids, which encode familial information but are by and large non indispensable for reproduction. Many of these plasmids can be transferred to other bacteriums by junction ( q. v. ) , a mechanism of familial exchange. Other mechanisms whereby bacteriums can interchange familial information include transduction, in which bacterial viruses ( see Bacteriophage ) transportation Deoxyribonucleic acid, and transmutation, in which DNA is taken into the bacterial cell straight from the environment. Bacterial cells multiply by binary fission ( q.v. ) ; the familial stuff is duplicated and the bacteria elongates, constricts near the center, and so undergoes complete division, organizing two girl cells basically indistinguishable to the parent cell. Therefore, as with higher beings, a given species of bacteriums reproduces merely cells of the same species. Some bacteriums divide every 20 to 40 proceedingss. Under favourable conditions, with one division every 30 proceedingss, after 15 hours a individual cell will hold produced approximately 1 billion offspring. This mass, called a settlement, may be seen with the bare oculus. Under inauspicious conditions some bacteriums may undergo a modified division procedure to bring forth spores, hibernating signifiers of the cell that can defy extremes of temperature and humidness. of Bacteria. chief groups of bacteriums exist: the saprophytic organisms, which live on dead animate being and vegetable affair ; and the symbionts, which live on or in populating animate being or vegetable affair. Saprophytes are of import because they decompose dead animate beings and workss into their constitutional elements, doing them available as nutrient for workss. Symbiotic bacteriums are a normal portion of many human tissues, including the alimental canal and the tegument, where they may be indispensable to physiological procedures. Such a relationship is called mutualistic. Other symbionts gain foods from their life host without doing serious harm ; this is commensalism. The 3rd type, parasites, can destruct the workss and animate beings on which they live. See besides Parasite. are involved in the spoilage of meat, vino, veggies, and milk and other dairy merchandises. Bacterial action may render such nutrients unpalatable by altering their composing. Bacterial growing in nutrients can besides take to nutrient poisoning such as that caused by Staphylococcus aureus or by Clostridium botulinus ( see Botulism ) . On the other manus, bacteriums are of great importance in many industries. The fermentative capablenesss of assorted species are manipulated for the production of cheese, yoghurt, pickles, and sauerkraut. Bacterias are besides of import in the production of bronzed leather, baccy, ensilage, fabrics, pharmaceuticals and assorted enzymes, polyoses, and detergents. are found in virtually all environments, where they contribute to assorted biological procedures. For illustration, they may bring forth visible radiation, such as the phosphorescence of dead fish ; and they may bring forth adequate heat to bring on self-generated burning in hayricks or in hop garners. By break uping cellulose, certain anaerobiotic signifiers evolve fen gas in dead pools ; by oxidising procedures, other bacteriums assist in organizing sedimentations of bog Fe ore, ocher, and manganese ore. See Bioluminescence. have an huge influence on the nature and composing of the dirt. One consequence of their activities is the complete decomposition of organic remains of workss and animate beings and of inorganic stone atoms. This action produces in the sum huge measures of works nutrient. In add-on, the leguminous workss that enrich dirt by increasing its N content do so with the aid of Rhizobium radicicola and other bacteriums that infect the roots of the workss and do nitrogen-fixing nodules to turn ( see Nitrogen Fixation ) . The photosynthetic procedure on which works life itself is based was about surely first established in bacteriums ; the recent find of an unusual photosynthesizing bacteria called Heliobacterium chlorum may assist in understanding this cardinal development in the history of life. Bacteria. 200 species of bacteriums are infective, or disease causation, for worlds. Pathogenicity varies widely among assorted species and is dependent on both the virulency of the peculiar species and the status of the host being. Among the more invasive bacteriums responsible for human disease are those that cause cholera, tetanus, gas sphacelus, Hansen’s disease, pestilence, bacillary dysentery, TB, pox, typhoid febrility, diphtheria, undulatory febrility, and several signifiers of pneumonia. Until the find of viruses, bacteriums were considered the causative agents of all infective diseases. infective effects of bacteriums on organic structure tissues may be grouped in four categories as follows: ( 1 ) effects of the direct local action of the bacteriums on the tissues, as in gas sphacelus, caused by Clostridium perfringens ; ( 2 ) mechanical effects, as when a mass of bacterium blocks a blood vas, doing an infective embolus ; ( 3 ) effects of the organic structure & # 8217 ; s response to certain bacterial infections on organic structure tissues, as in the forming of lung pits in TB, or devastation of bosom tissue by the organic structure & # 8217 ; s ain antibodies in arthritic febrility ; ( 4 ) effects of bacterial-produced toxins ( see Toxin ) , chemical substances that act as toxicants to certain tissues. Toxins are by and large species specific ; for illustration, the toxin responsible for diphtheria is different from the one responsible for cholera. . micro-organisms, including certain Fungis ( q.v. ) and some bacteriums, produce chemical substances that are toxic to specific bacteriums. Such substances, which include penicillin and streptomycin, are known as antibiotics ; they either kill the bacterium or forestall them from turning or reproducing. In recent old ages antibiotics have played an progressively of import function in medical specialty in the control of bacterial diseases. See Antibiotic. See besides Antiseptics ; Bacteriology ; Disease. J.H.N. ; A.J.G. & A ; D.M. For farther information on this subject, see ~Biblio. Biology, biochemistry, ~Biblio. Viruss, bacteriums, ~Biblio. Substance maltreatment. FIXATION, or industrial procedure by which molecular atmospheric N ( q.v. ) is converted into a chemical compound that is indispensable for works growing and is besides used in industrial chemical production. Fixation. most widely used and most productive of the dirt micro-organism capable of nitrogen arrested development are symbiotic bacteriums of the genus Rhizobium, which colonize and form nodules on the roots of leguminous workss such as trefoil, lucerne, and peas ( see Legume ) . These bacteriums obtain nutrient from the leguminous plant, which in bend is supplied with abundant N compounds. Dirts are sometimes inoculated with a peculiar species of Rhizobium to increase a legume harvest, which is frequently planted to refill the N depleted by other harvests. smaller sums of N are fixed in the dirt by free-living ( nonparasitic ) bacteriums such as the aerobes, which map in the presence of O, and bacteriums of the genera Klebsiella and Bacillus, which map without O. Some signifiers of bluish green algae besides fix N, such as the alga Anabaena, which, in mutualism with the H2O fern Azolla pinnata, is said to markedly increase rice outputs, as was the instance in Paddies in the Thai Binh part of northern Vietnam. The demand for fixed N in agribusiness today is far greater than can be supplied by natural biological procedures, and the production of nitrogen compounds from atmospheric N is a major chemical industry. Fixation. chief industrial nitrogen-fixation procedure today is the production of ammonium hydroxide ( q.v. ) by go throughing a mixture of atmospheric N and H over a metallic accelerator ( see Catalysis ) at 5000-6000 C ( 9320-11120 F ) . Ammonia is so oxidized to organize azotic acid, which is in bend combined with ammonium hydroxide to give ammonium nitrate, used chiefly in explosives and fertilisers ( see Fertilizer ) . In another method, cyanamide, which is used as a fertiliser or in the production of nitriles, is produced by go throughing atmospheric N over het Ca carbide in the presence of a accelerator. ( Gr. anti, & # 8220 ; against & # 8221 ; ; bios, & # 8220 ; life & # 8221 ; ) , substance produced by one being that is destructive to another. This procedure traditionally has been called antibiosis and is the antonym of mutualism ( q.v. ) . More specifically, an antibiotic is a type of chemotherapeutic agent, that is, it has a toxic consequence on certain types of disease-producing micro-organisms without moving perilously on the patient. Some chemotherapeutic agents differ from antibiotics merely in that they are non secreted by micro-organisms, as are antibiotics, but instead are made synthetically in a chemical research lab. Examples are quinine ( q. v. ) , used against malaria ; arsphenamine, used against pox ; the sulpha drugs ( q.v. ) , used against a broad assortment of diseases, notably pneumonia ; and the quinolones, used against hospital-derived infections ( zoonotic diseases ) . A few antibiotics, among them penicillin ( q.v. ) and Chloromycetin, have now been produced synthetically besides. . first observation of what would now be called an antibiotic consequence was made in the nineteenth century by the Gallic chemist Louis Pas teur, who discovered that certain saprophytic bacteriums can kill splenic fever sources. About 1900 the German bacteriologist Rudolf von Emmerich ( 1852-1914 ) isolated a substance called pyocyanase, which can kill the sources of cholera and diphtheria in the trial tubing. It was non utile, nevertheless, in bring arounding disease. In the 1920s the British bacteriologist Sir Alexander Fleming, who subsequently discovered penicillin, found a substance called muramidase in many of the secernments of the organic structure, such as cryings and perspiration, and in certain other works and carnal substances. Lysozyme has strong antimicrobic activity, but chiefly against harmless bacteriums. , the original of antibiotics, was discovered by accident in 1928 by Fleming, who showed its effectivity in research lab civilizations against many disease-producing bacteriums, such as those that cause gonorrhoea and certain types of meningitis and bacteriemia ( blood toxic condition ) ; nevertheless, he performed no experiments on animate beings or worlds. Penicillin was foremost used on worlds by the British scientists Sir Howard Florey and Ernst Chain during the 1940-41 winter. first antibiotic to be used in the intervention of human diseases was tyrothricin ( one of the purified signifiers of which was called gramicidin ) , isolated from certain dirt bacteriums by the American bacteriologist Rene Dubos in 1939. This substance is excessively toxic for general usage, but it is employed in the external intervention of certain infections. Other antibiotics produced by actinomycetes ( filiform and ramifying bacteriums ) happening in dirt have proved more successful. One of these, streptomycin ( q.v. ) , discovered in 1944 by the American microbiologist Selman Waksma

n and his associates, is effective against many diseases, including several in which penicillin is useless, especially tuberculosis. Use. then, such antibiotics as chloramphenicol, the tetracyclines, erythromycin, neomycin, nystatin, amphotericin, cephalosporins, and kanamycin have been developed and may be used in the treatment of infections caused by some bacteria, fungi, viruses, rickettsia, and other microorganisms. In clinical treatment of infections, the causative organism must be identified and the antibiotics to which it is sensitive must be determined in order to select an antibiotic with the greatest probability of killing the infecting organism. Developments. of bacteria have arisen that are resistant to commonly used antibiotics; for example, gonorrhea-causing bacteria that high doses of penicillin are not able to destroy may transfer this resistance to other bacteria by exchange of genetic structures called plasmids ( see Conjugation ). Some bacteria have become simultaneously resistant to two or more antibiotics by this mechanism. New antibiotics that circumvent this problem, such as the quinolones, are being developed. The cephalosporins, for instance, kill many of the same organisms that penicillin does, but they also kill strains of those bacteria that have become resistant to penicillin. Often the resistant organisms arise in hospitals, where antibiotics are used most often, especially to prevent infections from surgery. problem in hospitals is that many old and very ill persons develop infections from organisms that are not pathogenic in healthy persons, such as the common intestinal bacterium Escherichia coli. New antibiotics have been synthesized to combat these organisms. Fungus infections (q.v.) have also become more common with the increasing use of chemotherapeutic agents to fight cancer, and more effective antifungal drugs are being sought. search for new antibiotics continues in general, as researchers examine soil molds for possible agents. Among those found in the 1980s, for example, are the monobactams, which may also prove useful against hospital infections. Antibiotics are found in other sources as well, such as the family of magainins discovered (in the late 1980s) in frogs; although untested in humans as yet, they hold broad possibilities. have also been used effectively to foster growth in animals. Concern has arisen, however, that this widespread use of antibiotics in animal feed can foster the emergence of antibiotic-resistant organisms that may then be transmitted to human beings. An instance of one such transfer was documented in the U.S. in 1984. S.A.W. For further information on this topic, see ~Biblio. Substance abuse . , derived from the mold Penicillium notatum. The action of this antibiotic was first observed in 1928 by the British bacteriologist Alexander Fleming, but it was another ten years before penicillin was concentrated and studied by the British biochemist Ernst Chain, the British pathologist Sir Howard Florey, and other scientists. acts both by killing bacteria and by inhibiting their growth. It does not kill organisms in the resting stage but only those that are growing and reproducing. It is effective against a wide range of disease-bearing microorganisms, including pneumococci, staphylococci, streptococci, gonococci, meningococci, the clostridium of tetanus, and the syphilis spirochete. The drug has been successfully employed to treat such deadly diseases as subacute bacterial endocarditis, septicemia, and gas gangrene, and also gonorrhea, scarlet fever, and osteomyelitis. Toxic symptoms produced by penicillin are limited largely to allergic reactions which may be determined by scratch tests before administration of the drug. In 1980 a group of physicians announced that they had successfully desensitized several penicillin-allergic patients with a procedure that took only three hours; tests of the method on a wider scale were instituted. Penicillin. the effectiveness displayed by penicillin in curing a wide range of diseases, infections caused by certain strains of staphylococci could not be cured by the antibiotic as a result of the ability of the organism to produce an enzyme, penicillinase, capable of destroying the antibiotic. In addition, enterococci and many gramnegative bacilli known to cause respiratory and urinary-tract infections were found to be intrinsically resistant to the action of penicillin. Appropriate chemical treatment of a biological precursor to penicillin, isolated from bacterial cultures, resulted in the formation of a number of so-called semisynthetic penicillins. The most important of these are Methicillin and Ampicillin, the former remarkably effective against penicillinase-producing staphylococci and the latter not only active against all organisms normally killed by penicillin, but also inhibiting enterococci and most gram-negative bacilli. . strength and dosage of penicillin are measured in terms of international units. Each of these units is equal to 0.0006 g of the crystalline fraction of penicillin called penicillin G. In the early days of penicillin therapy, the drug was administered every three hours in small doses. More recently a preparation called benzathine penicillin G has been produced that provides detectable levels of antibiotic for as long as four weeks after a single intramuscular injection. It is useful for treatment of syphilis. S.A.W. , or chemical agents that prevent putrefaction, infection, and analogous changes in food and living tissue by destroying or arresting the development of microorganisms. Since ancient times food has been preserved by the use of antiseptic agents such as heat in cooking; niter, salt, and vinegar in corning and pickling; and wood smoke (containing creosote, chemically similar to carbolic acid) in the smoking of meats. In modern times the principal antiseptic agents used in the preservation of food are heat and cold in such processes as canning, pasteurization, and refrigeration. Irradiation is being investigated as a means of preserving food. practice of using antiseptics in the care and treatment of wounds was begun by the English surgeon Joseph Lister in 1868. Basing his work on the findings of the German physiologist Theodor Schwann and the French biochemist Louis Pasteur, Lister disinfected surgical and accidental wounds with a solution of carbolic acid, and in five years reduced the death rate from major amputations from 45 percent to about 12 percent. Many other antiseptics have come into use, among which the most important are bichloride of mercury, iodine, boric acid, alcohol, the hypochlorites, mercurochrome, and Merthio-late. Chlorine is used in the sterilization of water, especially in public water systems ( see Water Supply and Waterworks ) and swimming pools. , of bacteria (q.v.) , including their classification and the prevention of diseases that arise from bacterial infection. The subject matter of bacteriology is distributed not only among bacteriologists but also among chemists, biochemists, geneticists, pathologists, immunologists, and public-health physicians. . were first observed by the Dutch naturalist Antoni van Leeuwenhoek with the aid of a simple microscope of his own construction. He reported his discovery to the Royal Society of London in 1683, but the science of bacteriology was not firmly established until the middle of the 19th century. For nearly 200 years it was believed that bacteria are produced by spon taneous generation. The efforts of several generations of chemists and biologists were required to prove that bacteria, like all living organisms, arise only from other similar organisms. This fundamental fact was finally established in 1860 by the French scientist Louis Pasteur, who also discovered that fermentation and many infectious diseases are caused by bacteria. The first systematic classification of bacteria was published in 1872 by the German biologist Ferdinand J. Cohn, who placed them in the plant kingdom. They are now usually included in the kingdom Monera (q.v.) . In 1876 Robert Koch, who had devised the method of inoculating bacteria directly into nutrient media as a means of studying them, found that a bacterium was the cause of the disease anthrax. 1880, immunity against bacterial diseases has been systematically studied. In that year, Pasteur discovered by accident that Bacillus anthracis, cultivated at a temperature of 420 to 430 C (1080 to 1100 F), lost its virulence after a few generations. Later it was found that animals inoculated with these enfeebled bacteria showed resistance to the virulent bacilli. From this beginning date the prevention, modification, and treatment of disease by immunization (q.v.) , one of the most important modern medical advances. See Antitoxin . significant developments in bacteriology were the discoveries of the organisms causing glanders (1862), relapsing fever (1868), typhoid fever (1880), tetanus (1885), tuberculosis (1890), plague (1894), bacillary dysentery (1898), syphilis (1905), and tularemia (1912). . fundamental method of studying bacteria is by culturing them in liquid media or on the surface of media that have been solidified by agar (q.v.) . Media contain nutrients, varying from simple sugars to complex substances such as meat broth. To purify or isolate a single bacterial species from a mixture of different bacteria, solidified media generally are used. Individual cells dividing on the surface of solidified media do not move away from each other as they do in liquid, and after many rounds of replication they form visible colonies composed of tens of millions of cells all derived by binary fission (q.v.) from a single cell. If a portion of a colony is then transferred to a liquid medium, it will grow as a pure culture free of all other bacteria except the single species that was found in the colony. different species of bacteria so closely resemble one another in appearance that they cannot be differentiated from one another under the microscope. Various culture techniques have been developed to aid in species identification. Some media contain substances to inhibit the growth of many bacteria, but not the species of interest. Others contain sugars that some but not all bacteria can utilize for growth. Some media contain pH indicators that change color to indicate that a constituent of the media has been fermented, yielding acid end products. Gas production as an end product of fermentation can be detected by inoculating bacteria in solidified media in tubes rather than on plates. Sufficient gas production will result in the formation in the agar of bubbles that can easily be seen. Still other media are formulated to identify bacteria that produce certain enzymes that can break down constituents in the media; for example, blood agar plates, which can detect whether bacteria produce an enzyme to lyse, that is, dissolve, red blood cells. The various culture media and culture techniques are essential to the hospital laboratory, whose job it is to identify the cause of various infectious diseases. . or freezing kills many species of bacteria and causes others to become inactive. Heat or moist heat above a certain temperature kills all bacteria. Sterilization of many different objects, such as spacecraft and surgical instruments, are important facets of bacteriological work. See also Antiseptics . Examination. microscope is one of the most important tools used in studying bacteria. Dyeing or staining bacterial specimens or cultures was introduced in 1871 by the German pathologist Karl Weigert (1843-1905) and has greatly helped the bacteriologist in identifying and observing bacteria under the microscope. A bacterial specimen is first placed on a glass slide. After the specimen has dried, it is stained to render the organism easier to observe. Stains also stimulate reactions in certain bacteria. For example, the tuberculosis bacillus can be recognized only on the basis of its reaction to certain stains ( see Gram’s Stain ). Bacteriologists have been greatly aided by the electron microscope ( see Microscope ), which has far greater magnification powers than ordinary microscopes. Research. recent years, bacteriology has been greatly expanded from its concentration on disease-causing pathogens. The discovery that bacteria fix nitrogen in the root nodules of leguminous plants ( see Nitrogen Fixation ) has led to attempts to inoculate the roots of other plant strains and thereby increase soil fertility and the productivity of food crops. Some bacteria are able to digest petroleum and other hydrocarbons; others absorb phosphorus. These bacteria are being intensively investigated as possible aids in cleaning up oil spills and removing phosphorus from sewage sludge. Other bacteria may be more efficient than yeast at producing alcohol and are being explored in the search for new energy sources. Escherichia coli, a normal inhabitant of the human intestinal tract, is the most thoroughly studied of all organisms. Studies of the mechanisms of genetic exchange and the biology of plasmids and bacteriophages ( see Bacteriophage ) of E. coli have been crucial in understanding many aspects of DNA replication and the expression of genetic material. These studies have led to the ability to insert DNA from unrelated organisms into E. coli plasmids and bacteriophages and to have that DNA replicated by the bacteria, with the genetic information it contains expressed by the bacteria. It is thus possible for bacteria to become living factories for scarce biological products such as human insulin, interferon, and growth hormone. See Genetic Engineering . A.J.G. & D.M. For further information on this topic, see ~Biblio. Viruses, bacteria . ENGINEERING, of changing the inherited characteristics of an organism in a predetermined way by altering its genetic material. This is often done to cause microorganisms, such as bacteria or viruses, to synthesize increased yields of compounds, to form entirely new compounds, or to adapt to different environments. Other uses of this technology, which is also called recombinant DNA technology, include gene therapy, which is the supply of a functional gene (see Gene Therapy below) to a person with a genetic disorder ( see Genetic Disorders )or with other diseases, such as acquired immune deficiency syndrome (AIDS; q.v.) or cancer. engineering involves the manipulation of deoxyribonucleic acid, or DNA ( see Nucleic Acids ). Important tools in this process are so-called restriction enzy